Silicon dendritic web crystals are customarily grown from relatively small, shallow crucibles in order to obtain the temperature distribution and convective stability needed for this mode of crystal growth. As the crystal is pulled from the melt, the melt is depleted. Consequently, continuous addition of new silicon to the melt is needed to obtain extremely long crystals grown under steady state conditions. Not only must the silicon be added simply to supply silicon for long growth, but also to maintain a constant melt height which is one of the key parameters for achieving steady state growth. Moderate success in continuous growth has been achieved by the addition of small chunks of silicon (small cubes, "shot", etc.) to a feed compartment at one end of the crucible.
In the past, a single-walled barrier has been used to reduce the amount of disruptive waves and ripples occurring on the silicon melt surface as feed silicon is dropped into the melt. However, such barriers have not been particularly effective in eliminating adverse thermal interactions that occur between the feed and growth regions. The feed silicon, which is colder than the melt into which it is dropped, causes isolated pockets of cooler melt to form, increasing the danger of the silicon "freezing" on nucleation points within the growth region of the crucible, thereby seriously interfering with dendritic web crystal growth.